Spinal bone fusion system

ABSTRACT

A bi-directional fixating transvertebral (BDFT) screw/cage apparatus is provided. The BDFT apparatus includes an intervertebral cage including a plurality of internal angled screw guides, a plurality of screw members, and a cage indentation adjacent to the screw guides that independently or supplemented by other screw locking mechanisms prevents the screw members from pulling out of the internal angled screw guides. The internal angled screw guides orient a first screw member superiorly and a second screw member inferiorly. The intervertebral cage is adapted for posterior lumbar intervertebral placement, anterior lumbar intervertebral placement, anterio-lateral thoracic intervertebral placement, or anterior cervical intervertebral placement.

This application is a Continuation Application of U.S. patentapplication Ser. No. 16/160,824, filed Oct. 15, 2018, which is aContinuation Application of U.S. patent application Ser. No. 15/397,198,filed Jan. 3, 2017, which is a Continuation of U.S. patent applicationSer. No. 13/418,335, filed on Mar. 12, 2012, which is aContinuation-In-Part of application Ser. No. 13/103,994, filed May 9,2011, now U.S. Pat. No. 9,603,713, which is a Divisional of Ser. No.12/054,335, filed Mar. 24, 2008, now U.S. Pat. No. 7,972,363, which is aContinuation-In-Part of Ser. No. 11/842,855, filed Aug. 21, 2007, nowU.S. Pat. No. 7,942,903, which is a Continuation-In-Part of Ser. No.11/536,815, filed Sep. 29, 2006, now U.S. Pat. No. 7,846,188, which is aContinuation-In-Part of Ser. No. 11/208,644, filed Aug. 23, 2005, nowU.S. Pat. No. 7,704,279.

Application Ser. No. 13/418,335 is a Continuation-In-Part of Ser. No.13/084,543, filed Apr. 11, 2011, now U.S. Pat. No. 8,353,913, which is aDivisional of U.S. Pat. No. 11,842,855, filed Aug. 21, 2007, now U.S.Pat. No. 7,942,903. Application Ser. No. 13/418,335 claims the benefitof priority of 61/451,582, filed Mar. 10, 2011, 61/451,579, filed Mar.10, 2011, and 61/445,034, filed Feb. 21, 2011 and is aContinuation-In-Part of Ser. No. 13/401,829, filed Feb. 21, 2012, nowU.S. Pat. No. 9,744,052. Application Ser. No. 11/208,644 claims benefitof 60/670,231, filed Apr. 12, 2005. Application Ser. No. 13/401,829claims benefit of 61/445,034, filed Feb. 21, 2011.

Application Ser. No. 15/397,198 is a Continuation of Ser. No.13/418,323, filed Mar. 12, 2012, now U.S. Pat. No. 9,814,601, which is aContinuation-In-Part of Ser. No. 13/103,994, filed May 9, 2011, now U.S.Pat. No. 9,603,713, which is a Divisional of Ser. No. 12/054,335, filedMar. 24, 2008, now U.S. Pat. No. 7,972,363, which is aContinuation-In-Part of Ser. No. 11/842,855, filed Aug. 21, 2007, nowU.S. Pat. No. 7,942,903, which is a Continuation-In-Part of Ser. No.11/536,815, filed Sep. 29, 2006, now U.S. Pat. No. 7,846,188, which is aContinuation-In-Part of Ser. No. 11/208,644, filed Aug. 23, 2005, nowU.S. Pat. No. 7,704,279. Application Ser. No. 13/418,323 is aContinuation-In-Part of Ser. No. 13/084,543, filed Apr. 11, 2011, nowU.S. Pat. No. 8,353,913, which is a Divisional of Ser. No. 11/842,855,filed Aug. 21, 2007, now U.S. Pat. No. 7,942,903. Application Ser. No.13/418,323 claims benefit of 61/451,582, filed Mar. 10, 2011 and claimsbenefit of 61/451,579, filed Mar. 10, 2011 and is a Continuation-In-Partof Ser. No. 13/401,829, filed Feb. 21, 2012, now U.S. Pat. No.9,744,052. Application Ser. No. 13/401,829 claims benefit of 61/445,034,filed Feb. 21, 2011.

Application Ser. No. 15/397,198 is a Continuation-In-Part of Ser. No.13/401,829, filed Feb. 21, 2012, now U.S. Pat. No. 9,744,052, which is aContinuation-In-Part of Ser. No. 13/103,994, filed May 9, 2011, now U.S.Pat. No. 9,603,713, which is a Divisional of Ser. No. 12/054,335, filedMar. 24, 2008, now U.S. Pat. No. 7,972,363, which is aContinuation-In-Part Ser. No. 11/842,855, filed Aug. 21, 2007, now U.S.Pat. No. 7,942,903, which is a Continuation-In-Part Ser. No. 11/536,815,filed Sep. 29, 2006, now U.S. Pat. No. 7,846,188, which is aContinuation-In-Part of Ser. No. 11/208,644, filed Aug. 23, 2005, nowU.S. Pat. No. 7,704,279. Application Ser. No. 13/401,829 is aContinuation-In-Part of Ser. No. 13/084,543, filed Apr. 11, 2011, nowU.S. Pat. No. 8,353,913, which is a Divisional of Ser. No. 11/842,855,filed Aug. 21, 2007, now U.S. Pat. No. 7,942,903. Application Ser. No.13/401,829 claims benefit of 61/451,582, filed Mar. 10, 2011,61/451,579, filed Mar. 10, 2011, 61/445,034, filed Feb. 21, 2011.

FIELD OF DISCLOSURE

The present invention relates to a unique universal bi-directional screw(BDS) system, and in particular its application to the spine, alsoreferred to as bi-directional fixating transvertebral (BDFT) screw/cageconstructs which can be used as stand-alone intervertebral devices whichcombine the dual functions of an intervertebral spacer that can befilled with bone fusion material(s), as well as a bi-directionaltransvertebral bone fixating/fusion screw apparatus. In the posteriorlumbosacral and thoracic spine, intervertebral cage/BDFT screwconstructs can be used as stand-alone devices obviating the need forpedicle screw fixation in many but not all cases. In the anteriorcervical, thoracic and lumbosacral spine, intervertebral cage/BDFT screwconstructs can be used as stand-alone devices obviating the need foranterior or lateral (thoracic and lumbosacral) spinal plating, and/orsupplemental posterior pedicle screw fixation.

BACKGROUND

The history and evolution of instrumented spinal fusion in the entirehuman spine has been reviewed in related application Ser. No.12/054,335, filed on Mar. 24, 2008, Ser. No. 13/084,543, filed on Apr.11, 2011, Ser. No. 11/842,855, filed on Aug. 21, 2007, Ser. No.11/536,815, filed on Sep. 29, 2006, and Ser. No. 11/208,644, filed onAug. 23, 2005, the contents of which are hereby incorporated byreference in their entirety. Conventionally, the majority of posteriorcervical and almost all posterior thoracic and lumbosacral fusionsurgical techniques are typically supplemented with pedicle screwplacement. Conventionally, the majority of anterior cervical spinalfusions, and many anterio-lateral thoracic, and anterior oranterio-lateral lumbosacral fusions are supplemented with anterior oranterior-lateral spinal plating, and very often, in particular in thethoracic and lumbosacral spine, are supplemented with posterior pediclescrew instrumentation.

Complications of pedicle screw placement in cervical, thoracic andlumbosacral spine include duration of procedure, significant tissuedissection and muscle retraction, misplaced screws with neural and/orvascular injury, excessive blood loss, need for transfusions, prolongedrecovery, incomplete return to work, and excessive rigidity leading toadjacent segmental disease requiring further fusions and re-operations.Recent advances in pedicle screw fixation including minimally invasive,and stereotactic CT image-guided technology, and the development offlexible rods, imperfectly address some but not all of these issues.

Complications of anterior plating in the cervical spine includepotential plate, and/or screw esophageal compression, and misplacedscrews leading to neurovascular injury. Complications of anterior oranterior-lateral plating in the anterior lumbar spine include potentialdevastating injury to the major vessels due to chronic vascular erosionof the major vessels, or acute vascular injuries due to partial orcomplete plate and/or screw back out. Furthermore, for re-do surgeries,plate removal can be arduous, with potential complications of prolongedesophageal retraction, vascular injury and screw breakage. Recentadvances including diminishing the plate width and/or profile, andabsorbable plates, imperfectly address some but not all of these issues.

Complications of all conventional spinal anterior intervertebral deviceconstructs are their potential for extrusion in the absence of plating.Hence, they are supplemented with anterior plating to prevent extrusion.Complications of posterior lumbosacral intervertebral device constructin the presence or absence of supplemental pedicle screw fixation isdevice extrusion, and potential nerve root and/or vascular injuries.

SUMMARY

Herein described are multiple device embodiments which combine in asingle stand-alone construct the dual functions of: a) an intervertebralcage spacer which can be filled with bone fusion material maintainingdisc height, and, b) a bi-directional fixating/fusion transvertebralbody screw apparatus. These embodiments are described for posterior andanterior lumbar (and anterio-lateral thoracic) intervertebral placement,and anterior cervical intervertebral placement. The present inventionrecognizes the aforementioned problems with prior art apparatus andsolves these problems by, among other things, complimenting/improvingupon the designs illustrated in the aforementioned related applications.The present application provides an advanced and novel bi-directionalfixating transvertebral (BDFT) screw/cage apparatus with a verticalhemi-bracket locking screw mechanism which locks two adjacent screwsinto position, preventing back out by it's insertion into novelindentations on the upper superior and inferior sides of the screw boxwhich are aligned with the axial midpoint of the upper surface of thecage between two adjacent internalized cage screw guides/screws. Thesebrackets can be easily snapped into the cage indentations and removed bya bracket tool, for example, as described in U.S. Pat. No. 7,942,903,issued on May 17, 2011. This mechanism can be used not only for theseconstructs but also with any other device which requires a screw lockingmechanism, e.g., anterior cervical and lumbar spinal plates, and otherorthopedic/medical devices necessitating screw locking mechanisms. Theexemplary embodiments improve the probability of a solid fusion.

The exemplary embodiments of a bi-directional fixating transvertebral(BDFT) screw/cage apparatus provide as strong or stronger segmentalfusion as pedicle screws without the complications arising from pediclescrew placement, which include misplacement with potential nerve and/orvascular injury, violation of healthy facets, possible pedicledestruction, blood loss, and overly rigid fusions. By placing screwsacross the intervertebral space from vertebral body to vertebral body,engaging anterior and middle spinal columns and not the vertebral bodiesvia the transpedicular route thereby excluding the posterior spinalcolumn, then healthy facet joints, if they exist, are preserved. Becausethe present invention accomplishes both anterior and middle columnfusion, without rigidly fixating the posterior column, the presentinvention in essence creates a flexible fusion.

The present invention recognizes that the very advantage oftranspedicular screws which facilitate a strong solid fusion by rigidlyengaging all three spinal columns is the same mechanical mechanismwhereby complete inflexibility of all columns is incurred therebyleading to increasing rostral and caudal segmental stress which leads toan increased rate of re-operation.

Transvertebral fusion also leads to far less muscle retraction, bloodloss and significant reduction in operating room (O.R.) time. Thus, thecomplication of pedicle screw pull out, and hence, high re-operationrate associated with the current embodiment of flexible fusion pediclescrews/rods is obviated. The lumbosacral intervertebral cage/BDFT screwconstructs can be introduced via posterior, lateral, transforaminal oranterior interbody fusion approaches/surgical techniques. Although onecan opt to supplement these constructs with transpedicular screws therewould be no absolute need for supplemental pedicle screw fixation withthese operative techniques.

The anterior placement of a bi-directional fixating transvertebral(BDFT) screw/cage apparatus according to the embodiments of the presentinvention into the cervical and lumbar spine obviates the need forsupplemental anterior cervical or anterior lumbar plating. The solepurpose of these plates is to prevent intervertebral device extrusion.This function is completely obviated and replaced by the dualfunctioning bi-directional fixating transvertebral (BDFT) screw/cageapparatus, according to the present invention. The obvious advantage ofthis is a significant savings in operative time, and prevention ofinjuries associated with plating, in particular esophageal, large andsmall vessel injuries, and spinal cord nerve root injuries.

Because the embodiments of the bi-directional fixating transvertebral(BDFT) screw/cage apparatus engage a small percentage of the rostral andcaudal vertebral body surface area, multi-level fusions can be performedwith these devices.

Conventionally, failed anterior lumbar arthroplasties are salvaged bycombined anterior and posterior fusions. Intervertebral cage/BDFT screwconstructs may be utilized as a one-step salvage mechanism forfailed/extruded anteriorly placed lumbar artificial discs obviating theneed for supplemental posterior pedicle screws and/or anterior lumbarplating thereby significantly reducing and/or eliminating co-morbiditiesassociated with these other salvage procedures.

Likewise, anterior cervical intervertebral cage/BDFT screw constructplacement can be used to salvage failed anterior cervicalarthroplasties, and re-do fusions without having to supplement withcervical anterior plates, thereby reducing the morbidity of thisprocedure.

In addition, if a patient develops a discogenic problem necessitatinganterior cervical discectomy and fusion at a level above or below apreviously fused and plated segment, the present invention reduces oreliminates the need to remove the prior plate in order to place a newsuperior plate, because the function of the plate is replaced by thedual functioning intervertebral cervical construct, thereby reducing theoperating room time and surgical morbidity of this procedure.

Furthermore, because of the orientation and length of the BDFT screwswithin the intervertebral cage/BDFT constructs, multiple level fusionscan be easily performed.

For example, an exemplary embodiment is directed to an intervertebralcage spacer and bi-directional fixating/fusion transvertebral bodyscrew/cage apparatus. The apparatus can include an intervertebral cagefor maintaining disc height. The intervertebral cage may include a firstinternal screw guide and a second internal screw guide which narrow fromtop to bottom having an approximate angle of 25 degrees. However, theangles can vary up to forty degrees. The upper superior and inferiorwalls of the cage bordering the edge of the top of the cage, positionedmidway between the two central internal screw guides, have novelindentations for insertion of a vertical screw-locking hemi-bracket. Theapparatus may further include a first screw member having a screw with atapered end and a threaded body disposed within the intervertebral cage,a second screw member with a tapered end and a threaded body disposedwithin the intervertebral cage, and a vertical hemi-bracket covering themedial-vertical aspect of two adjacent screws which snaps into theindentations of the superior and inferior sides of the cage which arelocated at a midpoint between the two adjacent internalized screwguides. The locking mechanism may prevent the first screw member and thesecond screw member from pulling-out of the first internal screw guideand the second internal screw guide. The internal screw guides can beformed to narrow along a length of the screw guide in a direction ofdescent into the screw guides, thereby providing a preliminary firstlocking mechanism when the screws engage the screw guides and arecountersunk into the top of the cage. The exemplary embodiments of thevertical hemi bracket, which are locked into the cage and cover thescrew heads, can provide a secondary additive locking mechanism incombination with the first locking mechanism, thereby definitivelypreventing screw back out. In other embodiments, only the exemplaryembodiments of the vertical hemi bracket, which are locked into the cageand cover the screw heads (or a part of the screw heads), may beprovided to function as a primary locking mechanism for definitivelypreventing screw back out.

Another exemplary embodiment is directed to an integral intervertebralcage spacer and bi-directional fixating/fusion transvertebral body screwapparatus, including an intervertebral cage having a plurality ofinternal angled screw guides which are inserted into the posteriorlumbosacral disc space on either the left or right, or both sides.

In order to achieve screw bone penetration in such a constricted spacethe internalized screw guides/screw must be located very close to eachother and must be obliquely, not horizontally or vertically aligned. Theintervertebral cage may include a first internal screw guide and asecond internal screw guide which narrow from top to bottom having anapproximate angle of twenty five degrees. The angles can vary up toforty degrees. The upper superior and inferior walls of the cagebordering the top of the cage, midway between the two central internalscrew guides have novel indentations for insertion of a verticalscrew-locking hemi-bracket. The apparatus further includes a first screwmember having a screw with a tapered end and a threaded body disposedwithin the intervertebral cage, a second screw member with a tapered endand a threaded body disposed within the intervertebral cage, and avertical hemi-bracket covering the medial aspect of two adjacent screwswhich snaps into the superior and inferior sides of the cage which arelocated at a midpoint between the two adjacent internalized screwguides. This locking mechanism prevents the first screw member and thesecond screw member from pulling-out of the first internal screw guideand the second internal screw guide. The internal screw guides can beformed to narrow along a length of the screw guide in a direction ofdescent into the screw guides, thereby providing a preliminary firstlocking mechanism when the screws engage the screw guides and arecountersunk into the top of the cage. The exemplary embodiments of thevertical hemi bracket, which are locked into the cage and cover thescrew heads (or a part of the screw heads), can provide a secondaryadditive locking mechanism in combination with the first lockingmechanism, thereby definitively preventing screw back out. In otherembodiments, only the exemplary embodiments of the vertical hemibracket, which are locked into the cage and cover the screw heads, maybe provided to function as a primary locking mechanism for definitivelypreventing screw back out.

Another exemplary embodiment is directed to a method of inserting abi-directional fixating transvertebral (BDFT) screw/cage apparatusbetween a first vertebral body and a second vertebral body. The methodcan include measuring a dimension of a disc space between the firstvertebral body and the second vertebral body, determining that the discspace is a posterior or lateral lumbar disc space, an anterior lumbardisc space, or an anterior cervical disc space, selecting anintervertebral cage based on the measured dimension of the disc spaceand based on the determination of the disc space being the posteriorlumbar disc space, the lateral lumbar disc space, the anterior lumbardisc space, or the anterior cervical disc space, inserting the selectedintervertebral cage into a midline of the disc space until the selectedintervertebral cage is flush or countersunk relative to the firstvertebral body and the second vertebral body, inserting a first screwmember into a first internal screw guide of the selected intervertebralcage, inserting a second screw member into a second internal screw guideof the selected intervertebral cage, screwing the first screw member andthe second screw member into the first vertebral body and the secondvertebral body respectively, confirming a position and placement of theintervertebral cage relative to the first vertebral body and the secondvertebral body, and locking the first screw member and the second screwmember in a final position by its final turn when it's flush with thesurface of the cage. The vertical hemi bracket when inserted and lockedinto the cage indentations may cover the medial aspects of the screwsand therefore may prevent screw back-out when the screws are in theirfinal resting positions.

The posterior lumbar BDFT cage screw apparatus is uniquely designed inorder to get into the posterior space and obtain proper screwangulations. Two exemplary embodiments are described; one that isrectangular and one that is elliptical and concave mimicking theposterior intervertebral disc space. In both exemplary embodiments, theaxes of the internal screw guides are not horizontally or verticallyaligned as they are in the cervical embodiment. Their axes must beoblique one to the other, and the screw guides must be very close to oneanother in order for the screws to achieve proper angulation, trajectoryand vertebral body penetration in such a restricted posterior lumbarinter space.

In the embodiments having an anterior lumbar embodiment four screwdesign, in order to achieve maximal stability and to prevent subsidence,the lateral two screws penetrate the inferior vertebral body, and themiddle two screws project to the superior vertebral body.

In all BDFT embodiments, the screw angle guides have an approximatetwenty five degree angle. However, the angles can go up to fortydegrees. The angles can be variable or divergent i.e. two adjacentscrews can be angled laterally, medially or divergent with respect toeach other i.e. one angled laterally and the other angled medially.

In all embodiments the screw drill guide narrows such that the screwhead is countersunk into the cage and thus it can be locked even in theabsence of an additional screw locking mechanism. The screw lockingmechanism described herein is yet an additional mechanism guaranteeingthe prevention of screw back out/pull out.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are presented to aid in the description ofembodiments of the invention and are provided solely for illustration ofthe embodiments and not limitation thereof.

FIG. 1A illustrates a top, perspective (oblique) view of a verticalhemi-bracket screw locking device according to an embodiment of theinvention.

FIG. 1B illustrates a side (anterior-posterior) view of a verticalhemi-bracket screw locking device according to an embodiment of theinvention.

FIG. 1C illustrates a side (lateral) view of a vertical hemi-bracketscrew locking device according to an embodiment of the invention

FIG. 2A illustrates a top view of an anterior cervical intervertebralcage/BDFT screw construct according to an embodiment of the invention.

FIG. 2B illustrates a bottom, perspective (bottom isometric) view of ananterior cervical intervertebral cage/BDFT screw construct according toan embodiment of the invention.

FIG. 2C illustrates a side view of an anterior cervical intervertebralcage/BDFT screw construct according to an embodiment of the invention.

FIG. 2D illustrates a front, perspective (front isometric) view of ananterior cervical intervertebral cage/BDFT screw construct according toan embodiment of the invention.

FIG. 2E illustrates a top, perspective, partially exploded (bottomisometric) view of an anterior cervical intervertebral cage/BDFT screwconstruct according to an embodiment of the invention.

FIG. 2F illustrates a side, perspective, exploded view of an anteriorcervical intervertebral cage/BDFT screw construct with internalizedangled screw guides according to an embodiment of the invention.

FIG. 2G illustrates a top, perspective, exploded (top isometric) view ofan anterior cervical intervertebral cage/BDFT screw construct withvisualized internalized angled screw guides according to an embodimentof the invention.

FIG. 3A illustrates a top view of an anterior lumbar intervertebralcage/BDFT screw construct according to an embodiment of the invention.

FIG. 3B illustrates a bottom view of an anterior lumbar intervertebralcage/BDFT screw construct according to an embodiment of the invention.

FIG. 3C illustrates a front, perspective view of an anterior lumbarintervertebral cage/BDFT screw construct according to an embodiment ofthe invention.

FIG. 3D illustrates a side, perspective view of an anterior lumbarintervertebral cage/BDFT screw construct according to an embodiment ofthe invention.

FIG. 3E illustrates a side, perspective view of an anterior lumbarintervertebral cage/BDFT screw construct according to an embodiment ofthe invention.

FIG. 3F illustrates a top, partially exploded view of an anterior lumbarintervertebral cage/BDFT screw construct according to an embodiment ofthe invention.

FIG. 3G illustrates a perspective, exploded view of an anterior lumbarintervertebral cage/BDFT screw construct according to an embodiment ofthe invention.

FIG. 4A illustrates a top view of a posterior lumbar rectangularlydesigned intervertebral cage/BDFT construct according to an embodimentof the invention.

FIG. 4B illustrates a front, perspective view of a posterior lumbarrectangularly designed intervertebral cage/BDFT construct according toan embodiment of the invention.

FIG. 4C illustrates a side, perspective view of a posterior lumbarrectangularly designed intervertebral cage/BDFT construct according toan embodiment of the invention.

FIG. 4D illustrates a front, perspective view of a posterior lumbarrectangularly designed intervertebral cage/BDFT construct according toan embodiment of the invention.

FIG. 4E illustrates a top, perspective, partially exploded view of aposterior lumbar rectangularly designed intervertebral cage/BDFTconstruct according to an embodiment of the invention.

FIG. 4F illustrates a top, perspective, exploded view of a posteriorlumbar rectangularly designed intervertebral cage/BDFT constructaccording to an embodiment of the invention.

FIG. 5A illustrates a top view of a posterior lumbar ellipticallydesigned intervertebral cage/BDFT construct according to an embodimentof the invention.

FIG. 5B illustrates a front, perspective view of a posterior lumbarelliptically designed intervertebral cage/BDFT construct according to anembodiment of the invention.

FIG. 5C illustrates a side view of a posterior lumbar ellipticallydesigned intervertebral cage/BDFT construct according to an embodimentof the invention.

FIG. 5D illustrates a front, perspective (front isometric) view of aposterior lumbar elliptically designed intervertebral cage/BDFTconstruct according to an embodiment of the invention.

FIG. 5E illustrates a top, perspective, partially exploded view of aposterior lumbar elliptically designed intervertebral cage/BDFTconstruct according to an embodiment of the invention.

FIG. 5F illustrates a top, perspective, exploded view of a posteriorlumbar elliptically designed intervertebral cage/BDFT constructaccording to an embodiment of the invention.

FIG. 6A illustrates a perspective view of an intervertebral cageconstruct according to an embodiment of the invention.

FIG. 6B illustrates another perspective view of an intervertebral cageconstruct according to an embodiment of the invention.

FIGS. 6C(i) and 6C(ii) illustrate top, perspective view of anintervertebral cage construct according to an embodiment of theinvention.

FIG. 6D illustrates a top, perspective, exploded view of a positioningtool/screw guide/box expander.

FIG. 6E illustrates a superior oblique perspective view of thepositioning tool/drill guide/box expander component.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Aspects of the invention are disclosed in the following description andrelated drawings directed to specific embodiments of the invention.Alternate embodiments may be devised without departing from the scope ofthe invention. Additionally, well-known elements of the invention willnot be described in detail or will be omitted so as not to obscure therelevant details of the invention.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments. Likewise, the term “embodiments ofthe invention” does not require that all embodiments of the inventioninclude the discussed feature, advantage or mode of operation.

With reference to FIGS. 1A-6E, exemplary embodiments of the inventionwill now be described.

1. Exemplary Medical Device

Referring to FIGS. 1A-6E the above described problems of theconventional art can be solved in the cervical, thoracic and lumbosacralspines by insertion into the denuded intervertebral disc space multipleembodiments of a bi-directional fixating transvertebral (BDFT)screw/cage apparatus.

For example, FIGS. 1A-1C illustrate three-dimensional views of anexemplary embodiment of a vertical hemi-bracket 20. In this embodiment,the bracket 20 drapes over the screw heads (or at least a portionthereof) of screws 30, 40 (FIGS. 2A-5F) and is secured to (e.g., snapsinto or onto) a portion of a cage 10, 110, 210 (FIGS. 2A-5F) therebypreventing screws 30, 40 from backing out of the cage 10, 110, 210. Thebracket 20 can include a base 1 with arms 3 attached to the base 1. Thearms 3 a, 3 b can extend away from the base 1 such that cage 10, 110,210 interposes the arm 3 a, 3 b when the bracket 20 is engaged with thecage 10, 110, 210. In the illustrated exemplary embodiment, the arms 3can be attached on opposite sides/ends of the base 1. However, in otherembodiments, the arms 3 can be attached anywhere along the base 1. Thearms 3 can include, for example, a superior arm 3 a and an inferior arm3 b (e.g., a first arm and a second arm). In other embodiments, one ormore arms can be provided on either side of the base 1. For example, afirst arm (e.g., 3 a) can extend from a first side of the base 1 and asecond arm (e.g., 3 b) can extend from a second side (opposite side) ofthe base 1. In still other embodiments, a number of arms on the firstside of the base 1 can be different from a number of arms on the secondside of the base 1. For example, two arms can extend from a first sideof the base 1 and a single arm can extend from a second side (oppositeside) of the base 1, or two arms from a first side of the base 1 andthree arms from a second side (opposite side) of the base 1, etc. Othernumbers of arms and arrangements are possible within the spirit andscope of the invention.

The superior arm 3 a and inferior arm 3 b can snap onto or snap-lockinto the base 1. The superior arm 3 a and inferior arm 3 b can beresilient or flexible such that the arms 3 a, 3 b can be secured to thebase 1 by the resilient arms pressing against the sides of the cage 10,110, 210. The arms 3 a, 3 b can be secured by frictional forces or bycorresponding engaging features formed on a part of the arms 3 a, 3 band/or the cage 10, 110, 210.

For example, a portion of the superior arm 3 a and inferior arm 3 b cansnap-lock into indentations 70, 194, 290 of the superior and inferiorwalls of the cage 10 (FIGS. 2A-5F), respectively. In an exemplaryembodiment, each of the superior arm 3 a and inferior arm 3 b caninclude a medial protuberance 5 emanating and projecting from aninferior aspect of one or more of the arms 3 a, 3 b. The protuberances 5can snap into corresponding cage indentations 70, 194, 290 (FIGS.2A-5F), thereby locking the bracket 20 on the cage 20, 110, 210 andpreventing screws 30, 40 from backing out of the cage 10, 110, 210. Inanother example, a portion of the superior arm 3 a and inferior arm 3 bcan engage a portion of ridges 50 formed on the superior and inferiorsurfaces or edges of the lumbar cage 10.

FIGS. 2A-2G illustrate three-dimensional views of an embodiment of anexemplary anterior cervical intervertebral cage/BDFT construct 10. Inthis embodiment, the top portion of the cage 10 has indentations 70 thatare on the upper superior and inferior walls midway between the twointernalized screw guides/screws 80, 90 (FIGS. 2E-2G). The vertical hemibracket 20 snaps into these indentations 70.

The cage 10 also can include indentations or slots 12 on both sidesurfaces of the cage 10 for insertion of a prong of an implantation tool(see example cage and tool in FIG. 6D; the cage 10 can engage the toolin a similar manner), and more particularly, that engage the distalmedial oriented male protuberance of a lateral griper prong of animplantation tool.

In the illustrated embodiment, the indentations 70 are formed ondifference side surfaces from the indentations 12, for example, to avoidinterference with the insertion tool accessing the indentations 70 ofthe cage. However, in other embodiments, the indentations 70 and theindentations 12 can be formed on a same side surface. Also, theindentations 70 can be formed at locations other than midway between thescrew guides. The indentations 70 can have a variety of shapes anddepths. For example, the indentations 70 can have a shape correspondingto a shape of a medial protuberance 5 emanating and projecting from aninferior aspect of one or more of the arms 3 a, 3 b. In otherembodiments, the size and shape of the indentations 70 can be differentfrom the medial protuberance 5 of the arms 3 a, 3 b.

In an exemplary embodiment, a side surface of the cage 10 can beelliptically contoured when viewed from the side (FIG. 1C) to fit intothe bi-concave cervical disc space. The embodiment includes two screws30, 40. A first screw 30 is oriented rostrally (superiorly) and a secondscrew 40 is oriented caudally (inferiorly). The cage 10 can include acavity 60 for bone product placement.

The cage 10 can also include two built in internalized screw/drillguides 80, 90 (e.g., having approximately a 25 degree angulation; inother embodiments, the angulation can be up to 40 degrees), one for eachscrew 30, 40, which orient the screws 30, 40 bi-directionally inopposite directions (FIGS. 2E-2G). In an embodiment, the cage includesat least one screw guide 80 or 82 having a predetermined trajectory(e.g., preferably having a 25 degree angulation) that may make placementof all screws equally facile, more amenable to multi-level placement,and may diminish the need for external drill guides. In otherembodiments, the cage includes at least two screw guides 80, 82 having apredetermined trajectory (e.g., preferably having a 25 degreeangulation) that may make placement of all screws equally facile, moreamenable to multi-level placement, and may diminish the need forexternal drill guides. In other embodiments, the cage can include ascrew guide 80, 82 having another predetermined trajectory, such as anangulation of substantially 25 degrees (e.g., an angulation ranging from20 degrees to 30 degrees). In other embodiments, the cage can include ascrew guide 80, 82 having another predetermined trajectory, such as anangulation ranging from 20 degrees to 25 degrees, an angulation rangingfrom 25 degrees to 30 degrees, an angulation ranging from 25 degrees to35 degrees, an angulation ranging from 25 degrees to 35 degrees, anangulation ranging from 20 degrees to 40 degrees, an angulation rangingfrom 25 degrees to 40 degrees, etc. The embodiments of the cage caninclude one or more screw/drill guides 80, 82 having different anglesand/or different positions within the cage.

The cage 10 can include a screw guide tunnel exit 13 adjacent to thebone cavity 60 (FIG. 2D). The screw guide tunnel can be configured tonarrow along the length of the tunnel in a direction of descent into thecage 10. One of ordinary skill in the art will recognize that theinternalized screw/drill guides 80, 90 can have different degrees ofangulation and/or different positions within the cage 10. The built intunnels of the screw guides 80, 90 provide an important advantage ofensuring that only a single prescribed angled trajectory is possible fortransvertebral screw placement. The built in tunnels narrow (cone down)going downward. This facilitates the locking of the screw head to thetop of the cage even in the absence of the locking mechanism describedherein. Embodiments of the intervertebral cages 10 can be designed withinternalized screw/drill guides 80, 90 with different angles and/ordifferent positions within the cage. The angle and size of the screws30, 40 make them amenable to single or multi-level placement. Thesuperior and inferior surfaces or edges of the lumbar cage 10 caninclude ridges 50 or the like to facilitate integration and fusion withsuperior and inferior vertebral bodies. Any other method of boneintegration may be used, such as, e.g., spikes in varying sizes andgeometric arrays.

The embodiment can include a vertical hemi-bracket 20 which can be, forexample, snapped into the superior and inferior upper wall indentations70 in between the two screws guides 80, 90 located on top of the cage10. The vertical hemi-bracket 20 can be manufactured from a variety ofmaterials, such as titanium. When the screws 30, 40 are turned, thefirst screw member 30 and the second screw member 40 are locked in afinal position by its final turn when the screw head is flush with thesurface of the cage 10. The narrowing (coning down) of the internalscrew guides 80, 90 acts as an initial preliminary screw lockingmechanism by hugging the top of the screw at its junction with the screwhead. The vertical hemi-bracket 20 which covers the medial aspect orhead of both screws 30, 40 (or a portion thereof), and when snapped intothe cage indentations 70 prevents screw back out or pull out from thetunnels of the cage. These novel exemplary embodiments are quite uniqueand different from all other conventional screw locking mechanisms.

FIGS. 3A-3G illustrate three-dimensional views of an exemplaryembodiment of an anterior lumbar intervertebral cage/BDFT construct. Inthis embodiment, the cage 110 includes indentations 194 on the uppersuperior and inferior walls of the top portion of the cage 110 midwaybetween each of the two adjacent internalized screw guides 190, 192(FIGS. 3F-3G). The two vertical hemi brackets 120 can snap into each ofthe indentations 194 such that there is one bracket 120, for each pairof adjacent screws (i.e. one for screws 130, 140, and one for screws150, 160). In the embodiment, the screws 130, 140 and screws 150, 160are locked into the tunnels of the cage 110 with the two hemi-brackets120. The cage 110 can include additional indentations 12 on both sidesurfaces for insertion of prongs of an implantation tool. Further, cage110 can be larger than the cervical cage 10 and also can include anelliptically contoured sidewalls when viewed from the side to fit intothe bi-concave lumbar disc space (FIG. 3D). The cage 110 may includefour (4) horizontally aligned internalized screw guides 190, 192 forfour (4) screws 130, 140, 150, 160. The two lateral (left and right)screws 130, 160 can be oriented inferiorly, and the two middle screws140, 150 can be oriented superiorly. The axes of these guides 190, 192and screws 130, 140, 150, 160 are not perfectly horizontal with respectto each other. Each lateral screw guide/screw can be obliquely orientedwith respect to its adjacent medial screw guide/screw. In this manner,the exemplary embodiments can achieve the proper trajectory for bonepenetration along with the precise angle of the screw guides 190, 192.The screw guide tunnel exits 13 are illustrated in FIG. 3C and are incontinuity (connected) with the enlarged bone cavity 180. In theembodiment, the orientations of the four screw guides 190, 192 (andscrews 130, 140, 150, 160) are selected because of their symmetry andinherent stability.

The cage 110 can include a large cavity 180 for bone product placement.The cage 110 can include four built-in internalized screw/drill guides190, 192 (e.g., having an approximate 25 degree angulation; in otherembodiments, the angulation can be up to 40 degrees), one for each screw130, 140, 150, 160. Other embodiments of the intervertebral cage 110 canbe designed with internalized screw/drill guides 190, 192 with differentangles and/or different positions within the cage 110. The angle andsize of the screws 130, 140, 150, 160 make them amenable to single ormulti-level placement. The superior and inferior surfaces or edges ofthe cage 110 can include ridges 170 or the like to facilitateintegration and fusion with superior and inferior vertebral bodies.Other bone integration embodiments such as spikes can also be used. Inthis embodiment, there are no compartmental divisions in the cavity 180for bone product placement to maximize the quantity of bone for fusion.

In this embodiment, there is one vertical hemi bracket 120 for twoscrews 130, 140, 150, 160. Yet, in other embodiments, one vertical hemibracket 120 can be provided for each individual screw 130, 140, 150,160, or vertical hemi bracket 120 can be provided for two or more screws130, 140, 150, 160. The top of the cage 110 can include indentations 194on the superior and inferior upper sides of the cage 110 that areengaged the vertical hemi bracket 120 (e.g., by snapping a portion ofthe bracket into the indentation 194). The bracket 120 can bemanufactured from a variety of materials, such as bio-compatiblematerials, such as titanium.

In operation, when each of the screws 130, 140, 150, 160 are turned,each of the screws 130, 140, 150, 160 is locked in a final position by afinal turn of the screw when the screw head is flush with the surface ofthe cage 110. The narrowing of the internal screw guides 190, 192 canact as an initial preliminary screw locking mechanism by hugging the topof the screw/screw head interface (e.g., at its junction with the screwhead). One vertical hemi-bracket 120 covers the medial aspect (orportion thereof) of the first two screws, 130, 140, and another verticalhemi bracket 120 covers the medial aspect (or portion thereof) of thethird and fourth screws 150, 160. When the brackets are snapped and/orlocked into the cage indentations 194, screw back out or pull out of allfours screws can be prevented.

The internal screw guide tunnels 190, 192 can be formed to narrow alonga length of the screw guide in a direction of descent into the screwguides, thereby providing a preliminary first locking mechanism when thescrews 130, 140, 150, 160 engage the screw guides and are countersunkinto the top of the cage 110. The exemplary embodiments of the bracket120, which are locked into the cage 110 and cover at least a portion ofthe screw heads, can provide a secondary additive locking mechanism incombination with the first locking mechanism, thereby definitivelypreventing screw back out. In other embodiments, only the exemplaryembodiments of the bracket 120, which is locked into the cage 110 andcovers the screw heads (or a part of the screw heads), may be providedto function as a primary locking mechanism for definitively preventingscrew back out.

The exemplary embodiments are an evolutionary advance and improvement tothe apparatus illustrated in the aforementioned related applications ofApplicants, and are quite unique and different from all otherconventional locking mechanisms used for other types of anterior lumbarcages.

For example, a known conventional device has been provided that relatesto anterior placed lumbar implants with perforating screws. Suchpossible conventional devices conceivably may include a horseshoeimplant having a plurality of cylindrical holes with smooth innersurfaces and comprise only one stop for the heads of the bone screws tobe inserted into them. The placement of five cylindrical holes isoriented within the cage in a non-symmetric manner.

In comparison, the exemplary embodiments differ in many substantial waysfrom the conventional devices. For example, the exemplary embodimentsprovide a symmetric orientation of the screw holes, as well as a screwlocking mechanism. The exemplary embodiments also provide anangulation/trajectory (e.g., an approximate twenty five degreeangulation/trajectory) for preventing pull-out or back-out of the screwsthat would make placement of all screws in a manner which would lead tomaximum stability of the construct within the vertebral space, andobviate the need for external drill guides, and surgeon trajectoryangulation guess work.

In another possible conventional device, multiple embodiments of lumbarintervertebral implants are presented which include one with internallythreaded bore holes, another embodiment with a front plate mounted atthe front surface of the implant, and another embodiment with the frontplace displaceably configured to move vertically relative to theimplant. In addition, such devices may provide preferred borehole axesof 35-55 degrees. These conventional devices may have four screwperforations that are not aligned four in a row. Two of the screw holesare laterally placed on the left, one on top of each other, the top onewith a superior trajectory, and the bottom with an inferior trajectory.Likewise, two perforations are placed on the right, one on top of eachother, the top one with a superior trajectory and the bottom one with aninferior trajectory. The disclosed screw locking mechanism is a screwwith an external thread matching the internal borehole thread, or spiralsprings.

In comparison, the anterior lumbar construct of the exemplaryembodiments differs in many substantial ways from the conventionaldevices. The exemplary embodiments include a single cage construct withfour (4) internalized drill guides arranged horizontally in a row. Thelateral screw guides/screws are obliquely oriented with the respect totheir adjacent medial screw guides/screws. The middle two screws areoriented superiorly, and the lateral left and right screws are orientedinferiorly. This symmetric alignment of screws and orientations withinthe superior and inferior vertebral bodies (e.g., two middle superiorlyprojecting screws, and two laterally projecting inferior screws) makethe fixation to the superior and inferior vertebral bodies much moresymmetric and thus more stable, thereby preventing subsidence. In anexemplary embodiment, the cage includes a screw guide having apredetermined trajectory (e.g., an approximate trajectory of 25 degreesto 40 degrees) that makes placement of all screws equally facile, moreamenable to multi-level placement, and diminishes the need for externaldrill guides. Furthermore, the exemplary screw locking mechanism isunique and differs substantially from the conventional approach ofmatching screw/cage threads or spiral springs.

FIGS. 4A-4F illustrate three-dimensional views of an exemplaryembodiment of a posterior lumbar rectangular intervertebral cage/BDFTconstruct. In this embodiment, the top portion of the cage 210 includesindentations 290 that are positioned on the upper superior and inferiorwalls midway between the two internalized screw guides 270, 280 (FIG.4F). The vertical hemi bracket 220 snaps into these indentations 290.The cage 210 also includes additional indentations 12 on both sidesurfaces of the construct for the prong placement of an implantationtool. The screws 230, 240 perforate and orient in opposing superior andinferior directions.

The cage 210 can include a cavity 250 for bone product placement. In anexemplary embodiment, a side surface of the cage 210 can be ellipticallycontoured when viewed from the side (FIG. 4C) to fit into the bi-concavecervical disc space. In an exemplary embodiment, the top and bottomportions of the rectangular cage 210 can be elliptically contoured tonaturally fit into the bi-concave intervertebral disc space (FIG. 4C).The top portion of the cage can be square-shaped with equal width andlength. Also, in contrast to the cervical cage 10 of the previousembodiments, the depth dimension of the cage 210 far exceeds its width.The width is very narrow to prevent nerve root retraction/injury whenbeing placed posteriorly. The cage 210 can also include built-ininternalized screw/drill guides 270, 280 having a predetermined angledtrajectory (e.g., having an approximate 25 to 40 degree angulation), andtheir axes are not horizontal, but oblique one to the other and veryclose to each other (FIG. 4F). Each screw/drill guides 270, 280 canoccupy one corner of a square, obliquely oriented one to the other(FIGS. 4A and 4F). This is necessary to achieve proper screw angulation,trajectory and bone penetration in a narrow posterior lumbar interspace.One of the screw guides is angled rostrally (superiorly) (e.g., screwguide 270) and the other caudally (inferiorly) (e.g., screw guide 280).The intervertebral cages 210 can be designed with internalizedscrew/drill guides 270, 280 with different angles and/or differentpositions within the cage 210. Because the tunnel of the screw guide270, 280 narrows (cones down), when the screw 230, 240 is countersunk ontop of the cage 210, the screw 230, 240 can be preliminarily locked,even in the absence of this locking mechanism. The cage 210 can includethe narrowing tunnel and/or bracket 220 for preventing backing out ofthe screws. The angle and size of the screws 230, 240 make them amenableto single or multi-level placement. A screw guide exit tunnel can beformed adjacent to the bone cavity 250. The superior and inferiorsurfaces or edges can include ridges or the like to facilitateintegration and fusion with superior and inferior vertebral bodies. Thesurfaces could alternatively or in supplement, have additional boneintegration mechanisms, e.g. spikes having various sizes andarrangements. One of these constructs is placed posteriorly into theintervertebral space either on the left side, the right side, or bothsides.

An embodiment can also include a cage 210 which includes a vertical hemibracket locking mechanism 220 that can be, for example, snapped into theindentations 290 on the upper aspects of the superior and inferior sidesof the cage 210. The vertical hemi bracket locking mechanism 220 can bemanufactured from a variety of materials, such as bio-compatiblematerials, such as titanium. In operation, when the screws 230, 240 areturned, each of the first screw member 230 and the second screw member240 is locked in a final position by a final turn of the screw when thescrew head is flush with the surface of the cage 210. The narrowing ofthe internal screw guides 270, 280 can act as an initial preliminaryscrew locking mechanism. The vertical hemi-bracket 220 covering themedial aspect (or a portion thereof) of both screws 230, 240 whensnapped into the cage indentations 290 can prevent screw back out orpull out.

These novel exemplary embodiments are quite unique and different fromall other conventional screw locking mechanisms.

FIGS. 5A-5F illustrates three-dimensional views of an exemplaryembodiment of a posterior lumbar elliptical intervertebral cage/BDFTconstruct. In this embodiment, the top portion of the cage 210 includesindentations 290 that are positioned on the upper superior and inferiorwalls midway between the two internalized screw guides/screws 270, 280(FIG. 5F). The vertical hemi bracket 220 snaps into these indentations290. The cage 210 also includes additional indentations 12 on both sidesurfaces of the construct for the prong placement of an implantationtool. The screws 230, 240 perforate and orient in opposing superior andinferior directions.

The cage 210 can include a cavity 250 for bone product placement. In anexemplary embodiment, the entire body (or at least the side walls) ofthe cage 210 is elliptical when viewed from the side (FIG. 5C), asopposed to the top and bottom portions of the rectangular cage 210described in the previous embodiment (FIG. 4C). Further, in thisembodiment, the cage 210 can be contoured to naturally fit into thebi-concave intervertebral disc space (FIG. 5C).

The cage 210 can also include built-in internalized screw/drill guides270, 280 having a predetermined angled trajectory (e.g., having anapproximate 25-40 degree angulation), and their axes are not horizontalor vertical, but oblique one to the other and very close to each other.Each screw guide/screw occupies one corner of a square, obliquelyoriented one to the other (FIGS. 5A and 5F). In this manner, theexemplary embodiment can achieve proper screw angulation, trajectory,and bone penetration in so narrow a posterior lumbar interspace. One ofthe screw guides can be angled rostrally (superiorly) (e.g., screw guide270) and the other caudally (inferiorly) (e.g., screw guide 280). Theintervertebral cages 210 can be designed with internalized screw/drillguides 270, 280 with different angles and/or different positions withinthe cage 210. In an embodiment, the tunnel of the screw guide 270, 280narrows (cones down) and hugs the screw(s) 230, 240 at the screw-screwhead interface such that, when the screw is countersunk on top of thecage 210, the screw(s) 230, 240 can be preliminarily locked, even in theabsence of an additional locking mechanism. The exemplary embodiments ofthe bracket 220, which are locked into the cage 210 and cover at least aportion of the screw heads, can provide a secondary additive lockingmechanism in combination with the first locking mechanism provided bythe screw guides, thereby definitively preventing screw back out. Inother embodiments, only the exemplary embodiments of the bracket 220,which is locked into the cage 210 and covers the screw heads (or a partof the screw heads), may be provided to function as a primary lockingmechanism for definitively preventing screw back out. The angle and sizeof the screws 230, 240 make them amenable to single or multi-levelplacement. The screw guide exit tunnel 13 adjacent to the bone cavity250 is illustrated in FIG. 5B. The superior and inferior surfaces oredges can include ridges or the like to facilitate integration andfusion with superior and inferior vertebral bodies. One of theseconstructs is placed posteriorly into the intervertebral space either onthe left side, the right side, or both sides.

The embodiment can include a cage 210 which includes a vertical hemibracket locking mechanism 220 that can be, for example, snapped into theindentations 290 on the upper aspects of the superior and inferior sidesof the cage 210. The vertical hemi bracket locking mechanism 220 can bemanufactured from a variety of materials, such as titanium. When thescrews 230, 240 are turned, the first screw member 230 and the secondscrew member 240 are locked in a final position by its final turn whenthe screw head is flush with the surface of the cage 210. The narrowingof the internal screw guides 270, 280 act as an initial preliminaryscrew locking mechanism. The vertical hemi-bracket 220 covering themedial aspect (or a portion thereof) of both screws 230, 240 whensnapped into the cage indentations 290 prevent screw back out or pullout.

The exemplary embodiment of this novel intervertebral cage 210 is anevolutionary compliment to the apparatus illustrated in theaforementioned related applications. The novel cage 210 also is quiteunique and different from other conventional locking mechanisms used forother known cervical and lumbar anterior or posterior plate screws. Noother conventional posterior lumbar intervertebral cage BDFT/screwconstructs are known.

The embodiments have been described with reference to the exemplaryembodiments illustrated in the Figures. One of ordinary skill in the artwill recognize that the embodiments are not limited to the illustratedembodiments and any of the features of any of the embodiments can beincluded in any other embodiment.

2. Exemplary Surgical Method

Exemplary surgical steps for practicing one or more of the forgoingembodiments will now be described.

Anterior cervical spine placement of the intervertebral cage/BDFT screwconstruct 10 (FIG. 2 ) can be implanted via previously describedtechniques for anterior cervical discectomy and fusion. Some but not allof these techniques include, open, microscopic, closed endoscopic ortubular. Fluoroscopic or any other form of visualized guidance can beused for this procedure.

After the adequate induction of anesthesia, the patient is placed in asupine position. An incision is made overlying the intended disc spaceor spaces, and the anterior spine is exposed. A discectomy is performedand the endplates exposed. The disc height is measured and an anteriorcervical intervertebral cage of the appropriate disc height, width anddepth is selected. The central cavity 60 is packed with bone fusionmaterial, autologous bone graft, allograft, alone or in combination withany commercially available bone fusion promoting product. The cage 10 isthen inserted into the midline of the anterior disc space routinelyuntil it is flush or countersunk relative to the vertebral body aboveand below. The BDFT screws 30, 40 are then inserted into theinternalized rostrally (superiorly) and caudally (inferiorly) angledscrew guides 80, 90. A drill with or without a drill guide can be usedto prepare for screw placement. This is not absolutely necessary.Because the cage 10 has internalized screw guides 80, 90,self-drilling/self-tapping screws 30, 40 of the appropriately selectedlengths can be directly screwed into the vertebral bodies once placedinto the internalized drill-guided angled tunnels. The cage's screwguides 80, 90, which have internalized tunnels, direct the screws 30, 40into the superior and inferior vertebral bodies in the predeterminedangle of the internalized tunnels. There is no other angled trajectoryother than that which is built into the internalized screw guide/tunnelof the cage 10 that the screw 30, 40 can be oriented in. Hence,according to this exemplary embodiment, there is no absolute need forfluoroscopic guidance.

Once the surgeon is satisfied with the position and placement of thecage 10, the BDFT screws 30, 40 can then be locked into their finalpositions. When each of the BDFT screws 30, 40 are turned they penetrateand engage the bone until they are locked in a final position by itsfinal turn when the screw head is flush with the surface of the cage 10.The vertical hemi bracket 20 is then snapped into the upper superior andinferior cage indentations 70 covering the medial aspect of both screws.

Anterior or anteriolateral placement of thoracic or lumbar spineintervertebral cage/BDFT screw constructs 110 (FIG. 3 ) can be implantedvia previously described surgical techniques for anterior lumbardiscectomy, and transthoracic, anterior-lateral thoracic discectomy.Some but not all of these techniques include, open, microscopic, closedendoscopic or tubular. Fluoroscopic or any other form of visualizedguidance can be used for this procedure.

After the adequate induction of anesthesia and after the anterior spineis exposed a discectomy is performed and the endplates exposed. The discheight is measured and an anterior lumbar (or thoracic) intervertebralcage 110 of the appropriate disc height, width and depth is selected.The central cavity 180 is packed with bone fusion material, autologousbone graft, allograft, alone or in combination with any commerciallyavailable bone fusion promoting product. The cage 110 is then insertedinto the midline of the anterior disc space routinely until it is flushor countersunk relative to the vertebral body above and below. The fourBDFT screws 130, 140, 150, 160 are then inserted into the two middleinternalized rostrally (superiorly) and two lateral, caudally(inferiorly) angled screw guides 190, 192. A drill with or without adrill guide 190, 192 can be used to prepare for screw placement. This isnot absolutely necessary. Because the cage 110 has internalized screwguides 190, 192, self-drilling/self-tapping screws 130, 140, 150, 160 ofthe appropriately selected lengths can be directly screwed into thevertebral bodies once placed into the internalized drill-guided angledtunnels. The cage's internalized guides 190, 192, which haveinternalized tunnels, direct the screws 130, 140, 150, 160 into thesuperior and inferior vertebral bodies in the predetermined angle of theinternalized tunnels. There is no other angled trajectory other thanthat which is built into the internalized screw guide/tunnel of the cage110 that the screw 130, 140, 150, 160 can be oriented in. Hence there isno absolute need for fluoroscopic guidance.

Once the surgeon is satisfied with the position and placement of thecage 110, the BDFT screws 130, 140, 150, 160 can then be locked intotheir final positions. When each of the BDFT screws 130, 140, 150, 160are turned, they penetrate and engage the bone until they are locked ina final position by its final turn when the screw head is flush with thesurface of the cage 110. One vertical hemi bracket 120 is snapped intoits corresponding cage indentations 194 thereby covering the medialaspects of the first two screws 130, 140, and another vertical hemibracket 120 is snapped into its respective cage indentations 194 therebycovering the medial aspects of the third and fourth screws 150, 160.

Implantation of the posterior lumbar intervertebral cage/BDFT screwconstructs 210 (FIGS. 4 and 5 ) can be performed via previouslydescribed posterior lumbar interbody fusion (PLIF) or posteriortransforaminal lumbar interbody fusion (TLIF) procedures. The procedurescan be performed open, microscopic, closed tubular or endoscopictechniques. Fluoroscopic guidance can be used with any of theseprocedures.

After the adequate induction of anesthesia, the patient is placed in theprone position. A midline incision is made for a PLIF procedure, and oneor two parallel paramedian incisions or a midline incision is made forthe TLIF procedure. For the PLIF procedure, a unilateral or bilateralfacet sparing hemi-laminotomy is created to introduce the posteriorlumbar construct into the disc space after a discectomy is performed andthe space adequately prepared.

For the TLIF procedure, after unilateral or bilateral dissection anddrilling of the inferior articulating surface and the medial superiorarticulating facet the far lateral disc space is entered and acircumferential discectomy is performed. The disc space is prepared andthe endplates exposed.

The disc height is measured and a posterior lumbar intervertebralcage/BDFT screw construct 210 (FIGS. 4 and 5 ) of the appropriate discheight, width and depth is selected. The central cavity 250 is packedwith bone fusion material, autologous bone graft, allograft, alone or incombination with any commercially available bone fusion promotingproduct. Then one construct 210 is placed on either right or left sides,or one construct 210 each is placed into left and right sides. Theconstructs 210 are inserted such they are flush or countersunk relativeto the superior and inferior vertebral bodies. In addition to thecentral cavities 250 that are packed with bone product, theintervertebral space in between the constructs 210 can also be packedwith bone product for fusion.

The BDFT screws 230, 240 are then inserted into internalized rostrally(superiorly) and caudally (inferiorly) angled screw guides 270, 280. Adrill with or without a drill guide can be used to prepare for screwplacement. This is not absolutely necessary. Because the cage 210 hasinternalized screw guides 270, 280, self-drilling/self-tapping screws230, 240 of the appropriately selected lengths can be directly screwedinto the vertebral bodies once placed into the internalizeddrill-guided/angled tunnels 270, 280. The cage's internalized guides270, 280, which have internalized tunnels, direct the screws 230, 240into the superior and inferior vertebral bodies in the predeterminedangle of the internalized tunnels. There is no other angled trajectoryother than that which is built into the internalized screw guide/tunnel270, 280 of the cage 210 that the screw 230, 240 can be oriented in.Hence, unlike posterior placement of pedicle screws there is no absoluteneed for fluoroscopic or expensive and cumbersome, framelessstereotactic CT guidance.

Once the surgeon is satisfied with the position and placement of thecage 210, the BDFT screws 230, 240 can then be locked into their finalpositions. When each of the BDFT screws 230, 240 with ratcheted screwheads are turned, the BDFT screws 230, 240 penetrate and engage the boneuntil they are locked in a final position by its final turn when thescrew head is flush with the surface of the cage 210. The vertical hemibracket 220 is then snapped into the upper superior and inferior cageindentations 290 of the cage 210 covering the medial aspect of bothscrews 230, 240 and thus preventing screw back out or pull out.

The present inventions may provide effective and safe techniques thatovercome the problems associated with current transpedicular basedcervical, thoracic and lumbar fusion technology, as well as anteriorcervical, thoracic and lumbar plating technology, and for manydegenerative stable and unstable spinal diseases. These exemplaryembodiments may replace much pedicle screw, and anterior plating basedinstrumentation in many but not all degenerative spine conditions.

The speed and simplicity of placement of anterior and posterior lumbarintervertebral cage/BDFT screw constructs, and placement of anteriorcervical cage/BDFT screw constructs far exceeds that of current pediclescrew and anterior spinal plating technology. Furthermore, these deviceshave markedly significantly decreased risk of misguided screw placementand hence decreased risk of neurovascular injury, and blood loss. Thelumbar and cervical intervertebral cage/BDFT screw constructs all wouldhave decreased recovery time, and more rapid return to work timecompared to pedicle screw, and plating technology. These devices withgreat probability lead to similar if not equal fusion rates, withsubstantially less morbidity, and hence, overall, make them a majoradvance in the evolution of spinal instrumented technology leading toadvances in the compassionate care of the spinal patient.

FIGS. 6A, 6B, 6C(i), and 5C(ii) illustrate an exemplary embodiment ofexemplary cage 200. These features are shown for example purposes, arenot limited to the cage 200, and can be incorporated into any cageaccording to any of the embodiments described herein. As shown in FIGS.6C(i) and 6C(ii), the screw guides can be positioned within four (4)quadrants I, II, III, IV.

For example, the intervertebral cage can include a wall having an entryopening of the first integral screw guide and an entry opening of thesecond integral screw guide, wherein the wall of the cage can includefour quadrants delineated by a first axis and a second axis each lyingin a plane of the wall, and the first axis is at a right angle withrespect to the second axis, wherein the four quadrants include a firstquadrant, a second quadrant, a third quadrant, and a fourth quadrant,wherein the first quadrant and the fourth quadrant are opposed to thesecond quadrant and the third quadrant with respect to the first axis,and the first quadrant and the second quadrant are opposed to the thirdquadrant and the fourth quadrant with respect to the second axis,wherein the first quadrant is diagonally opposed to the third quadrant,and the second quadrant is diagonally opposed to the fourth quadrant,and wherein one of a majority of an area of the entry opening of thefirst integral screw guide is in the first quadrant and a majority of anarea of the entry opening of the second integral screw guide is in thethird quadrant; and the majority of the area of the entry opening of thefirst integral screw guide is in the second quadrant and the majority ofthe area of the entry opening of the second integral screw guide is inthe fourth quadrant.

In an embodiment, the intervertebral cage can include a wall having anentry opening of the first integral screw guide and an entry opening ofthe second integral screw guide, wherein the wall has four quadrantsdelineated by a first axis and a second axis each lying in a plane ofthe wall, and the first axis is at a right angle with respect to thesecond axis, wherein the four quadrants include a first quadrant, asecond quadrant, a third quadrant, and a fourth quadrant, wherein thefirst quadrant and the fourth quadrant are opposed to the secondquadrant and the third quadrant with respect to the first axis, and thefirst quadrant and the second quadrant are opposed to the third quadrantand the fourth quadrant with respect to the second axis, wherein thefirst quadrant is diagonally opposed to the third quadrant, and thesecond quadrant is diagonally opposed to the fourth quadrant, andwherein one of a center of the entry opening of the first integral screwguide is in the first quadrant and a center of the entry opening of thesecond integral screw guide is in the third quadrant; and the center ofthe entry opening of the first integral screw guide is in the secondquadrant and the center of the entry opening of the second integralscrew guide is in the fourth quadrant.

FIG. 6D illustrates an embodiment of an external drill/screw guide-boxexpander which assists in screw trajectory of the exemplary cage 200.The cage 200 can be a cage according to any of the embodiments describedherein, or an expanding cage, in which case an expanding Allen keycomponent can be used. The device can include, for example, an Allen key501 (e.g., for an expandable cage), a spring 502, a handle 503, agripper 504 having a gripper prong 506, which alternatively may includea male protuberance (e.g., a medially oriented mal protuberant extensionfor insertion into the lateral cage slot 12), and a screw guide 505.

FIG. 6E illustrates a superior oblique view of the screw guidedemonstrating insertions or grooves 509 for gripper prong 506 of thegripper 504 in FIG. 6D, built-in trajectory guides 511, 512 forinsertions of screws, and an opening 514 for an Allen key, in instancesin which an expandable cage is being used. In an embodiment, the Allenkey may not be present when a non-adjustable cage is being used. Inanother embodiment, the Allen key may be present even when an adjustablecage is being used, such that the tool is universal to various types ofcages.

The gripper 504 can include gripper prongs (e.g., medially oriented maleprotuberant extensions) 506 which insert into grooves 509 of the screwguide 505 and lateral slots (e.g., 12) of a cage, thereby perfectlyaligning them.

Hence, according to the exemplary embodiments, a cage can be providedthat has internal screw guides which have no gaps, and furthermore aninsertion tool can be provided that has an external screw guide thatfurther precisely guides the screws through the external tool screwguide, then into the internal implant screw guide guaranteeing theprecise predetermined angulation of the screws. The combination theinternal and external screw guides can create a long tunnel for a screwto enable a predetermined trajectory.

It is noted that the same trajectory can be provided by only with theinternal box screw guides; however, one of ordinary skill will recognizethat having the external screw guides as part of the tool furthermaintains the precise angle trajectory. The screw guide positions withinthe four (4) quadrants I, II, III, IV conform to the screw guidepositions within the four (4) quadrants I, II, III, IV of the screw box.

With reference to the drawings, it will be understood that an embodimentof the indentations or recesses for the screw holes in any of theexemplary cages can be configured such that the screw heads will restentirely within a peripheral side of a surface of the top portion of thecage (i.e., top surface). In this embodiment, the direction of the screwtunnel is from an anterior surface to a posterior of the top surface ofthe cage (i.e., the non-adjacent side).

In another embodiment, the indentations or recesses for the screw holescan be configured such that the screw heads will rest entirely withinthe peripheral side of the top surface of the cage. In this embodiment,the screw hole guide passes through the anterior-posterior axis of thetop surface. The guides core circumference for the screw thread issurrounded by the lateral wall masses, and surrounded by mass from thefront and rear surfaces (i.e., walls) of the cage.

In yet another embodiment, the indentations or recesses for the screwholes can be configured such that a recess for the screw holes areentirely within the peripheral side of the top surface of the box. Inthis embodiment, there is a through-hole for a screw which iscounter-bored to keep the screw head within an outer surface boundary ofthe cage and in a direction to prevent the screw from avoiding the frontor rear surfaces of the cage.

In yet another embodiment, the indentations or recesses for the screwholes can be configured such that a recess for the screw holes isentirely within the peripheral side of the front wall of the cage Inthis embodiment, the tunnel for the screws is such that when the screwfirst enters, the screw will be surrounded by mass from the lateralsides and mass from the upper and lower sides of the wall. The screwwill exit at the posterior end of the peripheral wall.

With reference to the drawings, it will be understood that an embodimentof the indentations or recesses for the screw holes can be configuredsuch that a position of the screws is suitable for posterior lumbarscrew holes.

For example, in an embodiment, the screw holes can be diagonal to eachother along a transversal line. The transversal line can be defined asthe line that would diagonally intersect and bypass the space betweenthe recess for the screw holes.

In another embodiment, the screw holes can be diagonally opposed and lieon a congruent angle to each other from the intersecting transversalline.

In another embodiment, the recess for the screw holes can be diagonaland perpendicular to each other within the outer plane.

In another embodiment, the recess for the screw holes can be diagonaland symmetrically constrained within the outer wall of the cage.

While the foregoing disclosure shows illustrative embodiments of theinvention, it should be noted that various changes and modificationscould be made herein without departing from the scope of the inventionas defined by the appended claims. The functions, steps and/or actionsof the method claims in accordance with the embodiments of the inventiondescribed herein need not be performed in any particular order.Furthermore, although elements of the invention may be described orclaimed in the singular, the plural is contemplated unless limitation tothe singular is explicitly stated.

What is claimed is:
 1. A spinal bone fusion system comprising: anintervertebral cage including: a top wall, a bottom wall, a first sidewall, and a second side wall defining a bone product placement space,the intervertebral cage defining a first vertebral body facing surfaceand a second vertebral body facing surface opposite the first vertebralbody facing surface; a first integral screw guide extending through thetop wall of the intervertebral cage, the first integral screw guidehaving a first predetermined angle; a second integral screw guideextending through the top wall of the intervertebral cage, the secondintegral screw guide having a second predetermined angle; and at leastone first indentation formed at least partially in a top surface of thetop wall of the intervertebral cage between the first integral screwguide and the second integral screw guide; a first screw memberconfigured to be disposed in the first integral screw guide at the firstpredetermined angle and at least partially within the intervertebralcage, the first screw member extending from a first entry opening formedin the top surface of the top wall of the intervertebral cage to a firstexit opening formed at least partially in a bottom surface of the topwall of the intervertebral cage and at least partially in the firstvertebral body facing surface; a second screw member configured to bedisposed in the second integral screw guide at the second predeterminedangle and at least partially within the intervertebral cage, the secondscrew member extending from a second entry opening formed in the topsurface of the top wall of the intervertebral cage to a second exitopening formed at least partially in the bottom surface of the top wallof the intervertebral cage and at least partially in the secondvertebral body facing surface; and a screw locking mechanism configuredto secure at least one of the first screw member and the second screwmember in one of the first integral screw guide and the second integralscrew guide, the screw locking mechanism comprising a flat cover portionand a coupling portion extending from the flat cover portion, the flatcover portion configured to only partially extend over a portion of anopening of the first integral screw guide or a portion of an opening ofthe second integral screw guide when the screw locking mechanism is in alocked position and coupled to the intervertebral cage by the couplingportion, wherein the coupling portion of the screw locking mechanismengages the at least one first indentation formed at least partially inthe top surface of the top wall of the intervertebral cage between thefirst integral screw guide and the second integral screw guide, whereineach of the first integral screw guide and the second integral screwguide is angled to orient the first screw member and the second screwbi-directionally in opposite directions, wherein the first screw memberincludes a screw head and a threaded body, wherein the second screwmember includes a screw head and a threaded body; and wherein, in thelocked position, a length of the flat cover portion in a direction fromthe first side wall to the second side wall is smaller than a distancemeasured from a center point of the first entry opening to a centerpoint of the second entry opening.
 2. The spinal bone fusion system ofclaim 1, wherein the screw locking mechanism is positioned within the atleast one first indentation between the first and second screw guideswhen the screw locking mechanism is in the locked position.
 3. Thespinal bone fusion system of claim 2, wherein the at least one firstindentation comprises: a superior indentation positioned on the firstvertebral body facing surface of the cage; and an inferior indentationpositioned on the second vertebral body facing surface of the cage; andwherein the coupling portion of the screw locking mechanism comprises aplurality of arms configured to engage the superior indentation and theinferior indentation, the plurality of arms comprising: a superior armincluding a first medial protuberance; and an inferior arm including asecond medial protuberance, wherein the superior and inferior armsattach to the corresponding superior and inferior indentations via thefirst and second medial protuberances.
 4. The spinal bone fusion systemof claim 2, wherein the flat cover portion covers and locks the firstand second screw members into the first and second integral screw guidesand prevents the first and second screw members from backing out of thefirst and second integral screw guides.
 5. The spinal bone fusion systemof claim 2, further comprising: a third screw member having a taperedend and a threaded body disposed within the cage; wherein the cagefurther includes: a third integral screw guide; and the screw lockingmechanism further comprises a second flat cover portion that covers andprevents the third screw member from pulling out of the third integralscrew guide.
 6. The spinal bone fusion system of claim 5, wherein thescrew locking mechanism further comprises a second coupling portioncomprising a plurality of arms, the plurality of arms engaging the atleast one first indentation to secure the second flat cover portion tothe intervertebral cage.
 7. The spinal bone fusion system of claim 5,wherein each of the first, second, and third integral screw guidesincludes a descending narrowing screw guide that narrows in a directionextending from top to bottom, and wherein the first, second, and thirdscrew members are disposed in each respective descending narrowing screwguide and countersunk in the top wall of the intervertebral cage suchthat each descending narrowing screw guide hugs each respective one ofthe each of the first, second, and third screw members to provide asecondary locking mechanism for each of the first, second, and thirdscrew members that is independent of the screw locking mechanism.
 8. Thespinal bone fusion system of claim 1, wherein each of the first integralscrew guide and the second integral screw guide includes a descendingnarrowing screw guide that narrows in a direction extending from top tobottom.
 9. The spinal bone fusion system of claim 8, wherein the firstscrew member and the second screw member are disposed in each descendingnarrowing screw guide and countersunk in the top wall of theintervertebral cage such that each descending narrowing screw guide hugseach respective one of the first screw member and the second screwmember to provide a secondary locking mechanism for each of the firstscrew member and the second screw member that is independent of thescrew locking mechanism.
 10. The spinal bone fusion system of claim 1,wherein the coupling portion of the screw locking mechanism extendsorthogonally from the flat cover portion.
 11. The spinal bone fusionsystem of claim 10, further comprising a first side slot formed in thefirst side wall, and a second side slot formed in the second side wall,wherein the coupling portion of the screw locking mechanism does notengage the first side slot or the second side slot.
 12. The spinal bonefusion system of claim 1, wherein the intervertebral cage furthercomprises a plurality of surface features on the first vertebral bodyfacing surface and the second vertebral body facing surface, at least aportion of the plurality of surface features are located on the firstvertebral body facing surface between the first exit opening and the topwall.
 13. The spinal bone fusion system of claim 1, wherein the firstpredetermined angle and the second predetermined angle are such that abottom surface of the flat cover portion of the screw locking mechanismcontacts an edge of the first screw member or the second screw member toprevent screw back out.
 14. The spinal bone fusion system of claim 1,wherein the coupling portion of the screw locking mechanism does notextend into the bone product placement space when the coupling portionengages the at least one first indentation.
 15. A bi-directionalfixating transvertebral (BDFT) screw/cage apparatus, comprising: anintervertebral cage configured for maintaining disc height, theintervertebral cage including a first integral screw guide, a secondintegral screw guide, and a third integral screw guide, each having apredetermined angled trajectory, each of the first integral screw guide,the second integral screw guide, and the third integral screw guidecountersunk into a top surface of a top wall of the intervertebral cage,the intervertebral cage further including at least one indentationformed at least partially in the top surface of the top wall of theintervertebral cage between the first screw guide and the second screwguide; a first screw member, a second screw member, and a third screwmember, each having a tapered end and a threaded body disposed withinthe intervertebral cage; and two screw locking mechanisms configured toprevent the first screw member, the second screw member, and the thirdscrew member from pulling-out of the first integral screw guide, thesecond integral screw guide, and/or the third integral screw guide,respectively; wherein each of the two screw locking mechanisms comprisesa body portion having a flat surface and a coupling portion extendingperpendicularly from the body portion, the body portion configured toonly partially cover a portion of at least the first screw member, thesecond screw member, or the third screw member when the screw lockingmechanism is in a locked position and is coupled to the at least oneindentation formed at least partially in the top surface of the top wallof the intervertebral cage by the coupling portion, wherein thepredetermined angled trajectory of the first screw member, second screwmember, and third screw member is such that the body portion isconfigured to contact an edge of the countersunk first screw member,countersunk second screw member, or countersunk third screw member toprevent screw back out; and wherein, in a locked position, a length of afirst body portion in a direction from a first side surface to a secondside surface of the intervertebral cage is smaller than a distancemeasured from a center point of an entry opening of the first integralscrew guide to a center point of an entry opening of the second integralscrew guide.
 16. The apparatus of claim 15, wherein the coupling portionof a screw locking mechanism of the two screw locking mechanisms snapsinto the at least one indentation and a body portion covers at least aportion of the first screw member and the second screw member.
 17. Theapparatus of claim 16, wherein the two screw locking mechanisms comprisevertical hemi-brackets.
 18. The apparatus of claim 15, wherein a firstscrew locking mechanism of the two screw locking mechanisms isconfigured to be positioned with the first body portion between thefirst integral screw guide and the second integral screw guide, and asecond screw locking mechanism of the two screw locking mechanisms isconfigured to be positioned with a second body portion between thesecond integral screw guide and the third integral screw guide when thetwo screw locking mechanisms are in a locked position.
 19. The apparatusof claim 18, wherein the first body portion does not overlap an entryopening of the third integral screw guide.
 20. The apparatus of claim15, the intervertebral cage further including a first indentation formedat least partially in the top surface of the top wall of theintervertebral cage between the first screw guide and the second screwguide and a second indentation formed at least partially in the topsurface of the top wall of the intervertebral cage between the secondscrew guide and the third screw guide.